Antibacterially finished textile products and shaped plastics have attracted attention in recent years. For example, garments, medical supplies and household goods conferred with antibacterial properties are currently available on the market.
Various resins, including polyamides (see Patent Documents 1, 2 and 4), polyacrylonitriles (see Patent Documents 3 to 5), polyesters (see Patent Document 4), polylactic acids (see Patent Document 6), polyvinylidene chlorides (see Patent Documents 7 and 8), and polystyrenes (see Patent Documents 8 to 11), are used as the resins making up such antibacterial products.
In these prior-art antibacterial products, an antibacterial finish is required to confer antibacterial properties to the resin.
Antibacterial substances used for such antibacterial finishing have generally included, for example: inorganic antibacterial agents containing metal ions such as copper, silver or zinc; or organic antibacterial agents such as benzalkonium chloride, organosilicon compounds or quaternary ammonium salts.
However, a drawback of inorganic antibacterial agents is that, when added to plastics, the influence of heat during the molding process or light irradiation deforms the plastic, markedly lowering the value of the product. Drawbacks of organic antibacterial agents include poor weather and chemical resistance, and a high acute oral toxicity.
In addition, the art of Patent Document 1 requires a polymer alloy preparation step, a melt-spinning step for obtaining polymer alloy fibers, and a step for removing the sea component from the polymer alloy fibers. These production steps are very complicated.
The nanofiber of Patent Document 2 can be obtained by electrostatic spinning, and so the step of manufacturing the fiber itself is simple. However, here too, a photocatalyst supporting step is separately required in order to achieve antibacterial and deodorizing effects.
Likewise, in the other antibacterial products in Patent Documents 3 to 11, a separate step involving the application of an antibacterial agent to fibers, particles, a sheet or the like is required.
Hence, in each of the prior-art disclosures, an antibacterial agent or photocatalyst conferring step that is separate from the fiber or film-forming steps is essential, which takes time, effort and cost.
Patent Documents 12 and 13 address this problem by disclosing a polylactic acid fiber which itself has antibacterial properties even without the addition of an antibacterial agent.
However, the antibacterial properties of these polylactic acid fibers are presumably due to the lactic acid monomer which is present at the surface of the micron order fibers, and thus similarly entail the addition of an antibacterial ingredient to fibers.
At the same time, textile products composed of polyurethane fibers have been widely used in hygiene products and the like.
For example, Patent Document 14 (U.S. Pat. No. 4,043,331) discloses an emergency wound dressing composed of polyurethane fibers which have a fiber diameter of from 0.1 to 25 μm and are obtained by electrostatic spinning.
Patent Document 15 (JP-A 2006-501373) discloses a nonwoven fiber assembly which includes aliphatic polyether polyurethane fibers with a fiber diameter of from 3 to 3,000 nm obtained by an electrostatic spinning process, and which is suitable in hygiene products such as medical dressings.
However, even in hygiene products composed of such polyurethane fibers, because the fibers themselves do not have antibacterial properties, when used, they must be treated with disinfectants at the point of care. Moreover, measures for maintaining a sterile state are required during storage as well.
Therefore, although the imparting of antibacterial properties is being carried out, as with the various types of resins mentioned above, conferring fibers with an antibacterial ability takes time, effort and cost.    Patent Document 1: JP-A 2005-36376    Patent Document 2: JP-A 2007-15202    Patent Document 3: JP-A 6-2272    Patent Document 4: JP-A 9-31847    Patent Document 5: JP-A 9-286817    Patent Document 6: JP-A 2000-248422    Patent Document 7: JP-A 11-279417    Patent Document 8: JP-A 2002-69747    Patent Document 9: JP-A 7-179694    Patent Document 10: JP-A 10-140472    Patent Document 11: JP-A 12-80560    Patent Document 12: JP-A 2001-40527    Patent Document 13: International Disclosure WO 2001/049584    Patent Document 14: U.S. Pat. No. 4,043,331    Patent Document 15: JP-A 2006-501373